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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-28 09:52:51 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-28 09:52:51 +0000
commit71507ca5d2410b11889ca963fafcd1bcad5044c3 (patch)
tree17e6d07243d49e29e4b75887e0d07f24ec2b66e8 /magic/scripts/create_filemagic_flac
parentInitial commit. (diff)
downloadfile-71507ca5d2410b11889ca963fafcd1bcad5044c3.tar.xz
file-71507ca5d2410b11889ca963fafcd1bcad5044c3.zip
Adding upstream version 1:5.44.upstream/1%5.44upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'magic/scripts/create_filemagic_flac')
-rwxr-xr-xmagic/scripts/create_filemagic_flac71
1 files changed, 71 insertions, 0 deletions
diff --git a/magic/scripts/create_filemagic_flac b/magic/scripts/create_filemagic_flac
new file mode 100755
index 0000000..0ecfb17
--- /dev/null
+++ b/magic/scripts/create_filemagic_flac
@@ -0,0 +1,71 @@
+#!/usr/bin/env bash
+
+## bash script to generate file magic support for flac.
+## https://github.com/file/file/blob/master/magic/Magdir/audio
+## below "#some common sample rates" (line 471), ie:
+## >>17 belong&0xfffff0 0x2ee000 \b, 192 kHz
+
+LANG=C
+
+target=magic/Magdir/audio
+
+## construct static list of sample rates based on standard crystal
+## oscillator frequencies.
+## 16.384 MHz Unknown audio application
+## (16384 kHz = 32 kHz * 512 = 32 * 2^9)
+## 22.5792 MHz Redbook/CD
+## (22579.2 kHz = 44.1kHz * 512 = 44.1 * 2^9)
+## also used: 11.2896, 16.9344, 33.8688 and 45.1584
+## 24.576 MHz DAT/Video
+## (24576 kHz = 48 kHz * 512 = 48 * 2^9)
+## also used: 49.1520
+
+## 33.8688 > 16.9344
+## 36.864 > 18.432000
+declare -a a_ground_fs=(16384000 22579200 24576000)
+
+## multiply ground clock frequencies by 1953 to get usable base
+## frequencies, for instance:
+## DAT/video: 24.576 MHz * 1000000 / 512 = 48000Hz
+## Redbook/CD: 22.5792 MHz * 1000000 / 512 = 44100Hz
+## use base rates for calculating derived rates
+declare -a samplerates
+## min divider: fs/n
+def_fs_n=512
+min_fs_n=4
+## start at base_fs/(def_fs*min_fs)
+## add each derived sample rate to the array
+for base_fs in "${a_ground_fs[@]}"; do
+ min_fs=$( echo "${base_fs} / ( ${def_fs_n} * ${min_fs_n} )" | bc)
+ ## max multiplier: fs*n*min_fs
+ max_fs_n=$(( 8 * min_fs_n ))
+ n=${max_fs_n}
+ while [[ ${n} -ge 1 ]]; do
+ sample_rate=$(( min_fs * n ))
+ samplerates+=(${sample_rate})
+ n=$(( n / 2 ))
+ done
+done
+
+declare -a stripped_rates
+declare -a lines
+for samplerate in "${samplerates[@]}"; do
+ ## use bc with sed to convert and format Hz to kHz
+ stripped_rate="$(LANG=C bc <<< "scale=5; ${samplerate} / 1000" | \
+ sed 's#[0\.]*$##g')"
+ ## only add uniq sample rates (should be necessary
+ if [[ ! "${stripped_rates[@]}" =~ ${stripped_rate} ]]; then
+ printf -v line ">>17\tbelong&%#-15x\t%#08x\t%s, %s kHz\n" \
+ "16777200" \
+ "$(( samplerate * 16 ))" \
+ "\b" \
+ "${stripped_rate}"
+ stripped_rates+=("${stripped_rate}")
+ lines+=("${line}")
+ fi
+
+done
+printf "## start cutting >>> \n"
+## print out the formatted lines
+printf "%s" "${lines[@]}" | sort -k5 -n
+printf "## <<< stop cutting\n"